Structure-function modification of soluble dietary fiber polysaccharides from lignified bamboo shoots through microwave-assisted enzymatic disruption of lignocellulosic barrier.

In lignified bamboo shoots, cell wall polysaccharides, mainly cellulose and hemicelluloses, are tightly associated with lignin to form a recalcitrant lignin-carbohydrate complex, which severely restricts the release and function of soluble dietary fiber (SDF) polysaccharides. To overcome this barrier, a microwave-assisted laccase-cellulase (MW-Lac-Cel) strategy was developed by combining microwave-induced structural loosening with sequential enzymatic deconstruction of lignin and cellulose. Dietary fiber composition and physicochemical properties were compared among different treatments. The isolated SDF was further characterized in terms of molecular weight, monosaccharide composition, microstructure, functional groups, and crystallinity, followed by evaluation of its in vitro bioactivities. Results demonstrated that MW-Lac-Cel increased the SDF content from 9.80 g/100 g to 35.34 g/100 g and induced the greatest reduction in lignocellulosic components. The obtained SDF exhibited a porous morphology, reduced crystallinity (18.56%), and a molecular weight of 152.66 kDa, accompanied by increases of 5.14% and 4.26% in arabinose and xylose, respectively. These structural changes also caused an approximately three-fold enhancement in antioxidant capacity and a cholesterol adsorption capacity of 21.35 mg/g. Overall, this study provides an efficient and targeted strategy for enhancing the yield and functional properties of SDF from highly lignified bamboo shoots.